A vehicle wheel and the method of manufacturing the wheel is known from German OS No. 2 442 785 wherein the wheel is cast in a single piece.
As shown in the profile drawings of that specification, the wheel has a drop-center rim which has a shoulder formed between the drop-center and the 15.degree. cone or dish surface lying adjacent to the wheel pan. This arrangement of the shoulder is a compromise between the amount of tire to be left out and the expense of the manufacturer since, on the one hand, it is more desirable to arrange the shoulder on the side of the pan (the pan being on the outside in simply tired front wheels so that when going around curves the outside wheel is then more strongly loaded or stressed, and the transverse forces run from the outside inwardly) but on the other hand the mold is more difficult and more complicated to manufacture.
With wheels wherein the pan is welded onto the completed rim, it is easy to weld the pan to the shoulder side, and thus to produce an optimum shape.
With cast wheels, however, great problems arise (insofar as the fastening of the pan onto the drop-center must be retained) since the sand mold must form a long wedge between the shoulder of the rim and the pan, which long or deep wedge cannot be formed to be sufficiently stable with the present day casting processes.
In particular, the cast element would break and deformations would occur. Furthermore, the danger of shrinkage with tight angles in the intersection between rim and pan is greater than with large angles. The use of an additional core, of sufficiently hard sand, would create additional costs.
If the pan is mounted directly on the shoulder, then an annular chamber appears, this time between the pan fastening and the drop-center, which would need to be filled by an additional core, a step which is undesirable because of the cost.